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Member of Technical Staff - Data Quality Engineer (Pre-training)

Reflection· Research
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San Francisco, CA, London, New York, NYFull-timePosted 9mo ago

About the role

Data Quality Engineer focused on upstream data quality for large language model pre-training. Owns data quality signals, designs automated QA methods, builds reusable QA pipelines, and monitors data quality to influence model performance.

Responsibilities

  • Own upstream data quality for LLM pre-training; as a specialist or generalist across languages and modalities
  • Partner closely with research and pre-training teams to translate requirements into measurable quality signals, and provide actionable feedback to external data vendors
  • Design, validate, and scale automated QA methods to reliably measure data quality across large campaigns
  • Build reusable QA pipelines that reliably deliver high-quality data to pre-training teams for model training
  • Monitor and report on data quality over time, driving continuous iteration on quality standards, processes, and acceptance criteria

Qualifications

  • Strong engineering fundamentals with experience building data pipelines, QA systems, or evaluation workflows for pre-training data
  • Detail-oriented with an analytical mindset, able to identify failure modes, inconsistencies, and subtle issues that affect data quality
  • Solid understanding of how data quality impacts pre-training, with the ability to translate quality concerns into concrete signals, decisions, and feedback
  • Experience designing and validating automated quality checks, including rule-based systems, statistical methods, or model-assisted approaches such as LLM-as-a-Judge
  • Comfortable working autonomously, owning problems end-to-end, and collaborating effectively with researchers, engineers, and operations partners

Skills

Required:PythonLarge dataset handlingLLM/Pre-training knowledgeCommunication

Benefits

  • Top-tier compensation: Salary and equity structured to recognize and retain our talent globally
  • Stock options: Everyone who joins and contributes to Reflection's success gets to share in the upside through stock options
  • Health & wellness: Comprehensive medical, dental, vision, and life, with an annual wellness allowance
  • Meals: Lunch and dinner are provided in the office daily
  • Life & family: 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys
  • Vacation days: Unlimited paid time off in the U.S. and 30 days in the U.K
  • Sponsorship support: We sponsor visas to help exceptional talent join our team and support long-term immigration pathways where applicable
  • Team building: We have regular off-sites, happy hours, and team celebrations
Last updated Oct 1, 2026. Interested? Apply on the company site.

About Reflection

Building frontier open intelligence

Building frontier open intelligence.

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